Keith Diaz, co-author of the study from Columbia University Medical Center, said: ‘We tend to think of sedentary behaviour as just the sheer volume of how much we sit around each day.

‘But previous studies have suggested that sedentary patterns – whether an individual accrues sedentary time through several short stretches or fewer long stretches of time – may have an impact on health.’

For the study, published in the Annals of Internal Medicine journal, Diaz and his team from seven US institutions fitted activity trackers to almost 8,000 people aged 45 and over from across America.

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Each participant wore the tracker for at least four days in a week, with their deaths tracked until September 2015 – revealing that, on average, participants were inactive for 12.3 hours of a 16-hour waking day.

Participants were inactive for an average of 12.3 hours in a 16-hour waking day (Picture: Getty)

Taking into account other facts such as age, sex, education, smoking and high blood pressure, researchers found that the overall length of inactivity was linked to changes in the risk of death from any cause – even when participants also did moderate to vigorous exercise.

Those who were sedentary for 13.2 hours a day were 2.6 times more likely to die early than those who spent less than 11.5 hours of their day inactive.

However, people with sedentary lifestyles can help to stave off an early death by moving around at least every half an hour.

‘If you have a job or lifestyle where you have to sit for prolonged periods of time, we suggest taking a movement break every half hour,’ Dr Diaz added. ‘This one behaviour change could reduce your risk of death, although we don’t yet know precisely how much activity is optimal.’

‘This study adds to the growing literature on how dangerous long periods of sitting are for our health and underscores a growing awareness among clinicians and researchers that sitting really is the new smoking,’ she said.

‘We need creative ways to ensure that we not only cut back on the total amount we sit, but also increase regular interruptions to sitting with bursts of activity.’